The long-term objective is to develop and translate to the clinic a PE-specific radioimaging probe, 99mTcHYNIC-Duramycin, shown to detect cellular apoptosis for the imaging of high-risk atherosclerotic plaque. The specific aims include 1) examining the affect of chelator spacer arms on the radiotracer, 2) developing a process to separate the two mono-conjugated isomers to examine their binding affinity, 3) comparing TPPTS and EDDA as co-ligands and use of mannitol as bulking agent to optimize the lyophilized vial kit for tracer preparation, and 4) demonstrating the aortic plaque imaging feasibility in a rabbit model using the optimized probe and final vial kit formulation. The systematic optimization of the probe followed by proof-of-concept in a rabbit aortic plaque model will provide a qualified molecular imaging probe for further phase II development. Phase II studies will include evaluation of the imaging probe in large animal models of coronary plaque and probe safety characterization to support an IND submission. The successful development of this atherosclerotic plaque radioimaging probe will provide an urgently needed tool for the clinical identification of high-risk coronary plaque, the cause of severe debilitating coronary events. Assessing the extent of atherosclerosis and identifying patients at high risk for an acute cardiovascular event is of significant clinical importance.